Control system for dental drills

Abstract

A control assembly for a dental apparatus wherein delivery of operating air, coolant air and coolant water to the dental hand piece is controlled through the operation of normally spring closed pilot valves which are operated to the open position by application of pilot air, delivery of which from the source of pressurized air is controlled by a foot operated valve so as to ensure delivery of coolant air or coolant water when needed when operating air is being delivered to the hand piece.

I claim: 
     
       1. A control assembly for controlling flow of operating air from a source of pressurized air and coolant fluid from a source of pressurized coolant to a pneumatically driven dental hand tool of dental drilling apparatus comprising: (a) first conduit means for delivery operating air from the pressurized air source to the hand piece,   (b) second conduit means for delivering pressurized coolant fluid from the pressurized fluid source to the hand piece,   (c) a pilot valve in each of the conduit means for controlling passage of operating air and coolant fluid there-through,   (d) each pilot valve having: (i) a closure element spring-urged to a normal closed position,   (ii) a closed chamber,   (iii) a valve operator in the closed chamber for moving the closure element to an open position upon application of air at selected pilot pressure to the chamber,     (e) a pilot air conduit means between the source of pressurized air and the chamber of each pilot valve,   (f) a foot-operated valve in said pilot air conduit means for controlling delivery of pilot air to the pilot valves,   (g) said pilot valves being arranged to open at the same selected pilot pressure so as to enable concurrent delivery of coolant fluid and operating air to the hand piece.   
     
     
       2. A control assembly as claimed in claim 1 including: (a) a diaphragm gate valve assembly in said first and second conduit means downstream of each pilot valve for controlling passage of operating air and coolant fluid to the hand piece, said diaphragm gate valve assembly being operable to a closed position under application of air at a selected signal pressure and operable to an open position under air at atmospheric pressure,   (b) a feed line extending between the source of pressurized air and the diaphragm gate valve assembly for delivering air at signal pressure to the diaphragm gate valve assembly,   (c) valve means in the feed line for controlling passage or signal air there-through, being operable to a first position in which the feed line is open to apply air signal pressure to the diaphragm gate valve assembly and a second position in which the feed line is closed,   (d) a hand piece holder adapted to receive the hand piece for storage,   (e) a valve operator associated with the holder for operating the valve means to a said first position when the hand piece is removed from the holder and for operating the valve means to said second position when the hand piece is applied to the holder.   
     
     
       3. A control assembly as claimed in claim 1 including a hand operated valve upstream of the pilot valve in the second conduit means selectively operable between open and closed positions for controlling the passage of coolant fluid through said second conduit means.